No P2P communication when using WebRTC?

Question

Node.js

Hello, please tell me about the situation:
We installed WebRTC on the server (ubuntu), began to connect from the local network - everything is fine, the connection is established, the handshake occurs and the video is transmitted via P2P. But if you connect to the local network, how the video turns into a black square of Malevich.
At first I thought that it was something with TURN servers, I replaced it with others and even raised my own, the situation has not changed.
Can anyone come across or can tell?